miR-203在慢性粒细胞白血病急变中的功能和机制研究

Blast crisis has been the most major cause of death in chronic myelocytic leukemia (CML) patients.The treatment strategy targeted only one point did not improve the prognosis at blasis crisis. MiRNAs which regulate biological functions through directly targeting multiple genes would become hopeful treatment targets at blast crisis. However, few studies have directly the functions of miRNAs in pathogenesis or treatment at blast crisis in CML. Using microarray we identified differential expression files in CML at chronic phase and blast crisis and the expression of miR-203 was the most significant at blast crisis. Introduction of miR-203 mimics decreased the proliferation of the bone marrow monoculear cells of blast crisis. Furthermore, several potential targets of miR-203 were highly up-regulated in bone marrow monoculear cells of patients at blast crisis, which suggested that it was creditable that miR-203 contribute to the malignant transformation of CML and be a hopeful treatment target. Based on the results, we will aim to further identify the roles and mechanisms of miR-203 in the inversion of malignant phenotype at blast crisis in CML. And we will assess the therapeutic value and significance of miR-203 at blast crisis. This study will make for clarifying the potential mechanism of blast crisis and provide a theoretical basis for the gene therapy in CML.

慢性粒细胞白血病（CML）急性变是导致CML患者死亡的最主要原因，临床针对单一性靶位的治疗效果不佳。miRNA对靶基因的调控具有“一对多”的特点，有望成为CML急变治疗的新靶点，但目前关于miRNA在CML急变中的特异性调控作用尚缺乏研究。前期工作中，我们对比了CML慢性期和急变期患者骨髓单个核细胞miRNA表达谱，结果发现miR-203在CML急变期显著降低，过表达miR-203能够抑制急变期患者骨髓单个核细胞的增殖，且miR-203的多个潜在靶基因在急变期骨髓细胞样本中高表达，提示miR-203可能是CML急变中关键的节点分子，有望成为新的治疗靶位。本课题拟以急变期患者骨髓单个核细胞作为细胞模型，研究miR-203在逆转CML急变期恶性表型中的功能及其分子机制，评价其作为CML急变治疗靶位的价值和意义，同时进一步丰富miRNA对CML急性变调控的理论认识。

慢性粒细胞白血病急性变是导致CML患者死亡的最主要原因，临床针对单一性靶位的治疗效果不佳。miRNA对靶基因的调控具有“一对多”的特点，有望成为CML急变治疗的新靶点，但目前关于miRNA在CML急变中的特异性调控作用尚缺乏研究。本研究发现：1.与CML慢性期相比，急变期患者骨髓单个核细胞中miR-203表达显著降低，且在CD34+的白血病干细胞中，miR-203表达下降更为显著；2.采用慢病毒感染的方式在CD34+白血病干细胞中过表达miR-203后，CD34+细胞增殖能力减弱，CD34+细胞克隆形成能力显著下降，细胞发生G1期阻滞，同时CD34+细胞凋亡增加；3.通过生物信息学预测，发现Msi-2是miR-203作用的靶基因之一，对比CML慢性期，在急变期患者骨髓细胞中Msi-2表达显著升高。采用慢病毒感染的方式下调CD34+细胞中Msi-2的表达，细胞增殖能力下降，克隆形成能力减弱，但细胞周期和凋亡未发生显著性变化。通过rescue实验恢复Msi-2的表达后，细胞增殖和克隆形成能力得以恢复。因此，miR-203通过下调Msi-2的表达抑制CD34+细胞增殖和自我更新能力。本课题首次发现在慢性粒细胞白血病急变期患者骨髓CD34+白血病干细胞中，miR-203通过直接靶向Msi2基因，调控其自我更新和增殖。miR-203可作为CML急变治疗的潜在靶点。